1. Field of the Invention
This invention relates to compounds for modulating protein kinase enzymatic activity for modulating cellular activities such as proliferation, differentiation, programmed cell death, migration and chemoinvasion. Even more specifically, the invention relates to thiazole compounds which inhibit, regulate and/or modulate Anaplastic Lymphoma Kinase (ALK) signal transduction pathways related to the changes in cellular activities as mentioned above, compositions which contain these compounds, and methods of using them to treat kinase, and more specifically, ALK-dependent diseases and conditions.
2. Summary of Related Art
Improvements in the specificity of agents used to treat cancer is of considerable interest because of the therapeutic benefits which would be realized if the side effects associated with the administration of these agents could be reduced. Traditionally, dramatic improvements in the treatment of cancer are associated with identification of therapeutic agents acting through novel mechanisms.
Protein kinases are enzymes that catalyze the phosphorylation of proteins, in particular, hydroxy groups on tyrosine, serine and threonine residues of proteins. The consequences of this seemingly simple activity on cell differentiation and proliferation are staggering; i.e., virtually all aspects of cell life in one way or another depend on protein kinase activity. Furthermore, abnormal protein kinase activity has been related to a host of disorders, ranging from relatively non-life threatening diseases such as psoriasis to extremely virulent diseases such as glioblastoma (brain cancer).
Protein kinases can be categorized as receptor type or non-receptor type. Receptor-type tyrosine kinases have an extracellular, a transmembrane, and an intracellular portion, while non-receptor type tyrosine kinases are wholly intracellular.
Receptor-type tyrosine kinases are comprised of a large number of transmembrane receptors with diverse biological activity. In fact, about 20 different subfamilies of receptor-type tyrosine kinases have been identified. One tyrosine kinase subfamily, designated the HER subfamily, is comprised of EGFR (HER1), HER2, HER3, and HER4. Ligands of this subfamily of receptors identified so far include epithelial growth factor, TGF-alpha, amphiregulin, HB-EGF, betacellulin and heregulin. Another subfamily of these receptor-type tyrosine kinases is the insulin subfamily, which includes INS-R, IGF-IR, and IR-R. The PDGF subfamily includes the PDGF-alpha and beta receptors, CSFIR, c-kit and FLK-II. Then there is the FLK family, which is comprised of the kinase insert domain receptor (KDR), fetal liver kinase-1 (FLK-1), fetal liver kinase-4 (FLK-4) and the fms-like tyrosine kinase-1 (flt-1). The PDGF and FLK families are usually considered together due to the similarities of the two groups. For a detailed discussion of the receptor-type tyrosine kinases, see Plowman et al., DN&P 7(6):334-339, 1994, which is hereby incorporated by reference.
The non-receptor type of tyrosine kinases is also comprised of numerous families, including Src, Frk, Btk, Csk, Abl, Zap70, Fes/Fps, Fak, Jak, Ack, and LIMK. Each of these families is then further sub-divided into varying subfamilies. For example, the Src family is one of the largest and includes Src, Yes, Fyn, Lyn, Lck, Blk, Hck, Fgr, and Yrk. The Src subfamily of kinases has been linked to oncogenesis. For a more detailed discussion of the non-receptor type of tyrosine kinases, see Bolen, Oncogene, 8:2025-2031 (1993), which is hereby incorporated by reference.
Since protein kinases and their ligands play critical roles in various cellular activities, deregulation of protein kinase enzymatic activity can lead to altered cellular properties, such as uncontrolled cell growth, associated with cancer. In addition to cancer, altered kinase signaling is implicated in numerous other pathological diseases. These include, but are not limited to: immunological disorders such as rheumatoid arthritis, graft-host diseases, multiple sclerosis, psoriasis; cardiovascular diseases such as atherosclerosis, myocardioinfarction, ischemia, stroke and restenosis; other inflammatory and degenerative diseases such as interbowel diseases, osteoarthritis, macular degeneration, diabetic retinopathy. Therefore, both receptor and non-receptor protein kinases are attractive targets for small molecule drug discovery.
One particularly attractive goal for therapeutic use of kinase modulation relates to oncological indications. For example, modulation of protein kinase activity for the treatment of cancer has been demonstrated successfully with the FDA approval of Gleevec® (imatinib mesylate, produced by Novartis Pharmaceutical Corporation of East Hanover, N.J.) for the treatment of Chronic Myeloid Leukemia (CML) and gastrointestinal stromal cancers (GIST). Gleevec is a c-Kit and Abl kinase inhibitor.
Modulation (particularly inhibition) of cell proliferation and apoptosis, two key cellular processes needed for tumor grown and survival (Matter, A., Drug Disc. Technol. 2001 6, 1005-1024), is an attractive goal for development of small-molecule drugs. Anti-proliferative and pro-apoptotic therapy represents a potentially important approach for the treatment of solid tumors and other disease associated with dysregulated cell growth, including ischemic coronary artery disease, diabetic retinopathy, psoriasis and rheumatoid arthritis.
One particularly attractive target for small-molecule modulation, with respect to antiproliferative and proapoptotic activity is Anaplastic Lymphoma Kinase (ALK). ALK is a novel receptor tyrosine kinase (RTK) belonging to the insulin receptor subfamily. ALK is present in tumors as a result of a (2:5)(p23′q35) chromosomal translocation, which produces fusion proteins between ALK and other proteins such as nucleophosmin (NPM). The immunocytochemical detection of the NPM-ALK fusion protein (and proteins encoded by other ALK fusion genes) has allowed the definition of a tumor classification as “ALK-positive lymphoma.” Eight variant ALK fusion proteins have been detected to date and all contain ALK kinase activity.
Activation of ALK occurs either by binding of the endogenous ALK mitogenic ligand, pleiotrophin, or by self-aggregation of the ALK fusion proteins, which causes autophosphorylation resulting in an increase of receptor dependent signaling. ALK activation causes increased cell proliferation and apoptosis via activation of the PKC, MAPK and PIP3K pathways.
ALK fusion proteins or full length ALK proteins have been detected not only in ALK-positive lymphomas but also in B-cell lymphoma, neuroblastoma and inflammatory myofibroblastic tumors. Recent analysis shows that ALK expression is a marker for a lymphoma subtype with a good prognosis and there are reports of a five-year survival of approximately 80% for ALK-positive lymphomas, compared to 15-45% for ALK-negative lymphomas of anaplastic large cell morphology. (See Morris, et al., Brit. J. Hematol. (2001) 113, 275-295; Stein, et al., Blood (2000) 96, 3681-3695; Drexler, et al. Leukemia (2000) 14, 1533-1559). Thus modulation of ALK is desirable as a means to treat certain cancers and cancer-related disease.
Accordingly, the identification of small-molecule compounds that specifically inhibit, regulate and/or modulate the signal transduction of kinases, particularly ALK, is desirable as a means to treat or prevent disease states associated with abnormal cell proliferation and apoptosis, and is an object of this invention.